It is known that reinforcing fillers such as carbon black and silica greatly improve the strength and fatigue properties of elastomeric compounds. It is also known that chemical interaction occurs between the elastomer and the filler. For example, good interaction between carbon black and highly unsaturated elastomers such as polybutadiene (BR) and styrene butadiene copolymers (SBR) occurs because of the large number of carbon-carbon double bonds present in these copolymers. Butyl elastomers may have only one tenth, or fewer, of the carbon-carbon double bonds found in BR or SBR, and compounds made from butyl elastomers are known to interact poorly with carbon black. For example, a compound prepared by mixing carbon black with a combination of BR and butyl elastomers results in domains of BR, which contain most of the carbon black, and butyl domains which contain very little carbon black. It is also known that butyl compounds have poor abrasion resistance.
Canadian Patent Application 2,293,149 illustrates that it is possible to produce filled butyl elastomer compositions with improved properties by combining halobutyl elastomers with silica and specific silanes. These silanes act as dispersing and bonding agents between the halogenated butyl elastomer and the filler. However, one disadvantage of the use of silanes is the evolution of alcohol during the process of manufacture and potentially during the use of the manufactured article produced by this process. Additionally, silanes significantly increase the cost of the resulting manufactured article.
Co-pending application CA 2,339,080 discloses a process for preparing compositions containing halobutyl elastomers and organic compounds containing at least one basic nitrogen-containing group and at least one hydroxyl group in which there is enhanced interaction between the elastomer and a filler, especially a mineral filler. Of interest were compounds containing primary amine and hydroxyl groups such as ethanolamine. While solving the problem of enhancing the interaction between elastomer and filler, said compositions have to be processed carefully to prevent any undesirable scorch of the composition. Those skilled in the art understand the term scorch as premature crosslinking of the composition during processing.
Co-pending Canadian Patent Application CA-2,412,709 discloses a process for preparing compositions containing halobutyl elastomers, organic compounds containing at least one basic nitrogen-containing group and at least one hydroxyl group, and hydrated metal halogenides. In this process there is enhanced interaction between the elastomer and a filler, especially a mineral filler with improved scorch safety. The application also discloses filled halobutyl elastomer compositions containing halobutyl elastomers, organic compounds containing at least one basic nitrogen-containing group and at least one hydroxyl group, and one or more hydrated metal halogenides. Those compositions have improved properties when compared to known carbon black-filled halobutyl elastomeric compositions combined with an enhanced scorch safety.